List of countries by proven oil reserves

Proven oil reserves are those quantities of petroleum which, by analysis of geological and engineering data, can be estimated with a high degree of confidence to be commercially recoverable from a given date forward from known reservoirs and under current economic conditions. Some statistics on this page are disputed and controversial — different sources (like OPEC, CIA World Factbook and oil companies) give different figures. Some of the differences reflect the different types of oil included. Different estimates may or may not include oil shale, mined oil sands, or natural gas liquids. Because proven reserves include oil recoverable under current economic conditions, nations may see large increases in proven reserves when known, but previously uneconomic deposits become economic to develop. In this way, Canada's proven reserves increased suddenly in 2003 when the oil sands of Alberta were seen to be economically viable. Similarly, Venezuela's proven reserves jumped in the late 2000s when the heavy oil of the Orinoco Belt was judged economic.